Technical Field
The present disclosure generally relates to the processing of digital images, including tone mapping.
Description of the Related Art
In tone mapping, a group of digital image processing techniques are used, for example, to generate, from a high dynamic range image where a large number of different tones (or degrees of intensity) are available to depict a scene, an image of lower dynamic range where a smaller number of tones is available to depict the scene.
Tone mapping techniques may be used in combination with methods for obtaining high dynamic range images where several images of a same scene are successively acquired with different sensor integration times, after which these images are merged into a high dynamic range image where the values of the pixels corresponding to the darkest areas of the scene are based on the values of the corresponding pixels of the images acquired with the highest integration times, and the values of the pixels corresponding to the brightest areas of the scene are based on the values of the corresponding pixels of the images acquired with the shortest integration times. The high dynamic range image may be coded over a relatively large number of bits. To make this image compatible with equipment having but a limited number of tones to depict a scene (for example, a display device), it may be provided to use tone mapping techniques to decrease the dynamic range of the image while keeping the appearance of a high dynamic range image.
Tone mapping techniques may also be used to modify the tone distribution in an image without decreasing its dynamic range, for example, to apply special effects, a gamma function, etc.